Variable displacement swash plate type compressor

ABSTRACT

A variable displacement swash plate type compressor includes a displacement control valve. The displacement control valve includes a drive force transmitting member, a valve member having a first valve body, a valve chamber, which accommodates the first valve body, an accommodating chamber, which communicates with a control pressure chamber, a pressure sensing mechanism, which adjusts the valve opening degree of the first valve body, a communicating chamber, which is located on the opposite side of the pressure sensing mechanism from the valve chamber, and a second valve body, which is located in the pressure sensing mechanism and selectively opens and closes the communicating chamber. When the current supply to the electromagnetic solenoid is stopped and the pressure in the suction pressure zone in the communicating chamber is higher than a predetermined pressure, the pressure sensing mechanism contracts to open the second valve body.

BACKGROUND OF THE INVENTION

The present invention relates to a variable displacement swash platetype compressor, in which pistons engaged with a swash plate arereciprocated by a stroke corresponding to the inclination angle of aswash plate.

Such a compressor is disclosed in Japanese Laid-Open Patent PublicationNo. 1-190972. The compressor has a housing that accommodates a swashplate and a movable body, which is coupled to the swash plate to alterthe inclination angle of the swash plate. A control pressure chamber isformed in the housing. As control gas is introduced to the controlpressure chamber, the pressure inside the control pressure chamber ischanged. This moves the movable body along the axis of the rotary shaft.As the movable body is moved along the axis of the rotary shaft, theinclination angle of the swash plate is changed.

Specifically, when the pressure in the control pressure chamber isincreased, the movable body is moved toward a first end in the axialdirection of the rotary shaft. The movement of the movable bodyincreases the inclination angle of the swash plate. When the pressure inthe control pressure chamber is lowered, the movable body is movedtoward a second end in the axial direction of the rotary shaft. Themovement of the movable body decreases the inclination angle of theswash plate. As the inclination angle of the swash plate is reduced, thestroke of the pistons is reduced. Accordingly, the displacement isdecreased. In contrast, as the inclination angle of the swash plate isincreased, the stroke of the pistons is increased. Accordingly, thedisplacement is increased. The variable displacement swash plate typecompressor has a displacement control valve, which controls the pressurein the control pressure chamber.

In such a variable displacement swash plate type compressor, when theswitch of the vehicle air conditioner is turned off and the currentsupply to the electromagnetic solenoid of the displacement control valveis stopped, changes in the pressure in the suction pressure zone maymaintain the inclination angle of the swash plate at an angle greaterthan the minimum inclination angle. When the air conditioner switch isturned on again and the current supply to the electromagnetic solenoidis resumed, the displacement is abruptly increased. This increases theload on the variable displacement swash plate type compressor.Therefore, the inclination angle of the swash plate is preferablyminimized when the air conditioner switch is turned off and the currentsupply to the electromagnetic solenoid is stopped.

SUMMARY OF THE INVENTION

Accordingly, it is an objective of the present invention to provide avariable displacement swash plate type compressor that is capable ofminimizing the inclination angle of a swash plate when current supply tothe electromagnetic solenoid is stopped and maintaining the minimuminclination angle.

To achieve the foregoing objective and in accordance with one aspect ofthe present invention, a variable displacement swash plate typecompressor is provided that includes a housing having a crank chamber, aswash plate, a piston, a movable body, a control pressure chamber, and adisplacement control valve. The swash plate is accommodated in the crankchamber. The swash plate receives a drive force from a rotary shaft torotate and is capable of changing its inclination angle relative to therotary shaft. The piston is engaged with the swash plate. The movablebody is coupled to the swash plate and changes the inclination angle ofthe swash plate. The control pressure chamber is defined in the housingby the movable body. Pressure in the control pressure chamber is changedby introducing control gas therein so that the movable body is moved inthe axial direction of the rotary shaft. The displacement control valvecontrols the pressure in the control pressure chamber. The piston isreciprocated by a stroke that corresponds to the inclination angle ofthe swash plate. The displacement control valve includes a drive forcetransmitting member, a valve member, a valve chamber, an accommodatingchamber, a pressure sensing mechanism, a communicating chamber, and asecond valve body. The drive force transmitting member is driven by anelectromagnetic solenoid. The valve member has a first valve body. Thefirst valve body adjusts an opening degree of discharge passage thatextends from the control pressure chamber to a suction pressure zone.The valve chamber accommodates the first valve body and communicateswith the suction pressure zone. The accommodating chamber communicateswith the control pressure chamber. The pressure sensing mechanism isaccommodated in the accommodating chamber and integrated with the valvemember. By sensing a pressure in the suction pressure zone that acts onthe valve member, the pressure sensing mechanism extends or contracts inthe moving direction of the drive force transmitting member, therebyadjusting the valve opening degree of the first valve body. Thecommunicating chamber is located on the opposite side of the pressuresensing mechanism from the valve chamber and communicates with thesuction pressure zone. The second valve body is located in the pressuresensing mechanism and selectively opens and closes the communicatingchamber. When a current supply to the electromagnetic solenoid isstopped and the pressure in the suction pressure zone in thecommunicating chamber is higher than a predetermined pressure, thepressure sensing mechanism contracts in the moving direction of thedrive force transmitting member, thereby opening the second valve body.

Other aspects and advantages of the present invention will becomeapparent from the following description, taken in conjunction with theaccompanying drawings, illustrating by way of example the principles ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best beunderstood by reference to the following description of the presentlypreferred embodiments together with the accompanying drawings in which:

FIG. 1 is a cross-sectional side view illustrating a variabledisplacement swash plate type compressor according to one embodiment;

FIG. 2 is a cross-sectional view of a displacement control valve whenthe swash plate is at the minimum inclination angle;

FIG. 3 is a cross-sectional view of the displacement control valve whenthe swash plate is at the maximum inclination angle;

FIG. 4 is a cross-sectional side view illustrating the variabledisplacement swash plate type compressor when the swash plate is at themaximum inclination angle;

FIG. 5 is a cross-sectional view illustrating the displacement controlvalve in a state when the pressure in the suction chamber exceeds apredetermined pressure in a state in which current is not supplied tothe electromagnetic solenoid;

FIG. 6 is a cross-sectional view illustrating the displacement controlvalve when current is supplied to the electromagnetic solenoid in astate where the bellows is contracted;

FIG. 7 is a cross-sectional view of the displacement control valve,showing a state in which the valve seat member has been moved toward thecommunicating chamber;

FIG. 8 is a cross-sectional view showing a displacement control valveaccording to another embodiment; and

FIG. 9 is a cross-sectional view showing a displacement control valveaccording to a further embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A variable displacement swash plate type compressor 10 according to oneembodiment will now be described with reference to FIGS. 1 to 7. Thevariable displacement swash plate type compressor 10 is adapted to beused in a vehicle air conditioner.

As shown in FIG. 1, the variable displacement swash plate typecompressor 10 includes a housing 11, which is formed by a first cylinderblock 12 located on the front side (first side) and a second cylinderblock 13 located on the rear side (second side). The first and secondcylinder blocks 12, 13 are joined to each other. The housing 11 furtherincludes a front housing member 14 joined to the first cylinder block 12and a rear housing member 15 joined to the second cylinder block 13.

A first valve plate 16 is arranged between the front housing member 14and the first cylinder block 12. Further, a second valve plate 17 isarranged between the rear housing member 15 and the second cylinderblock 13.

A suction chamber 14 a and a discharge chamber 14 b are defined betweenthe front housing member 14 and the first valve plate 16. The dischargechamber 14 b is located radially outward of the suction chamber 14 a.Likewise, a suction chamber 15 a and a discharge chamber 15 b aredefined between the rear housing member 15 and the second valve plate17. Additionally, a pressure adjusting chamber 15 c is formed in therear housing member 15. The pressure adjusting chamber 15 c is locatedat the center of the rear housing member 15, and the suction chamber 15a is located radially outward of the pressure adjusting chamber 15 c.The discharge chamber 15 b is located radially outward of the suctionchamber 15 a. The discharge chamber 14 b, 15 b are connected to eachother through a discharge passage (not shown). The discharge passage isin turn connected to an external refrigerant circuit (not shown). Thedischarge chambers 14 b, 15 b are discharge pressure zones.

The first valve plate 16 has suction ports 16 a connected to the suctionchamber 14 a and discharge ports 16 b connected to the discharge chamber14 b. The second valve plate 17 has suction ports 17 a connected to thesuction chamber 15 a and discharge ports 17 b connected to the dischargechamber 15 b. A suction valve mechanism (not shown) is arranged in eachof the suction ports 16 a, 17 a. A discharge valve mechanism (not shown)is arranged in each of the discharge ports 16 b, 17 b.

A rotary shaft 21 is rotationally supported in the housing 11. A part ofthe rotary shaft 21 on the front side (first side) extends through ashaft hole 12 h, which is formed to extend through the first cylinderblock 12. Specifically, the front part of the rotary shaft 21 refers toa part of the rotary shaft 21 that is located on the first side in thedirection along the axis L of the rotary shaft 21 (the axial directionof the rotary shaft 21). The front end of the rotary shaft 21 is locatedin the front housing member 14. A part of the rotary shaft 21 on therear side (second side) extends through a shaft hole 13 h, which isformed in the second cylinder block 13. Specifically, the rear part ofthe rotary shaft 21 refers to a part of the rotary shaft 21 that islocated on the second side in the direction in which the axis L of therotary shaft 21 extends. The rear end of the rotary shaft 21 is locatedin the pressure adjusting chamber 15 c.

The front part of the rotary shaft 21 is rotationally supported by thefirst cylinder block 12 at the shaft hole 12 h. The rear part of therotary shaft 21 is rotationally supported by the second cylinder block13 at the shaft hole 13 h. A sealing device 22 of lip seal type islocated between the front housing member 14 and the rotary shaft 21. Thefront end of the rotary shaft 21 is connected to and driven by anexternal drive source, which is a vehicle engine E in this embodiment,through a power transmission mechanism PT. In the present embodiment,the power transmission mechanism PT is a clutchless mechanism (forexample, a combination of a belt and pulleys), which constantlytransmits power.

In the housing 11, the first cylinder block 12 and the second cylinderblock 13 define a crank chamber 24. A swash plate 23 is accommodated inthe crank chamber 24. The swash plate 23 receives drive force from therotary shaft 21 to be rotated. The swash plate 23 also tilts along theaxis L of the rotary shaft 21 with respect to the rotary shaft 21. Theswash plate 23 has an insertion hole 23 a, through which the rotaryshaft 21 can extends. The swash plate 23 is assembled to the rotaryshaft 21 by inserting the rotary shaft 21 into the insertion hole 23 a.

The first cylinder block 12 has first cylinder bores 12 a (only one ofthe first cylinder bores 12 a is illustrated in FIG. 1), which extendalong the axis of the first cylinder block 12 and are arranged about therotary shaft 21. Each first cylinder bore 12 a is connected to thesuction chamber 14 a via the corresponding suction port 16 a and isconnected to the discharge chamber 14 b via the corresponding dischargeport 16 b. The second cylinder block 13 has second cylinder bores 13 a(only one of the second cylinder bores 13 a is illustrated in FIG. 1),which extend along the axis of the second cylinder block 13 and arearranged about the rotary shaft 21. Each second cylinder bore 13 a isconnected to the suction chamber 15 a via the corresponding suction port17 a and is connected to the discharge chamber 15 b via thecorresponding discharge port 17 b. The first cylinder bores 12 a and thesecond cylinder bores 13 a are arranged to make front-rear pairs. Eachpair of the first cylinder bore 12 a and the second cylinder bore 13 aaccommodates a double-headed piston 25, while permitting the piston 25to reciprocate in the front-rear direction. That is, the variabledisplacement swash plate type compressor 10 of the present embodiment isa double-headed piston swash plate type compressor.

Each double-headed piston 25 is engaged with the periphery of the swashplate 23 with two shoes 26. The shoes 26 convert rotation of the swashplate 23, which rotates with the rotary shaft 21, to linearreciprocation of the double-headed pistons 25. In each first cylinderbore 12 a, a first compression chamber 20 a is defined by thedouble-headed piston 25 and the first valve plate 16. In each secondcylinder bore 13 a, a second compression chamber 20 b is defined by thedouble-headed piston 25 and the second valve plate 17.

The first cylinder block 12 has a first large diameter hole 12 b, whichis continuous with the shaft hole 12 h and has a larger diameter thanthe shaft hole 12 h. The first large diameter hole 12 b communicateswith the crank chamber 24. The crank chamber 24 and the suction chamber14 a are connected to each other by a suction passage 12 c, whichextends through the first cylinder block 12 and the first valve plate16.

The second cylinder block 13 has a second large diameter hole 13 b,which is continuous with the shaft hole 13 h and has a larger diameterthan the shaft hole 13 h. The second large diameter hole 13 bcommunicates with the crank chamber 24. The crank chamber 24 and thesuction chamber 15 a are connected to each other by a suction passage 13c, which extends through the second cylinder block 13 and the secondvalve plate 17.

A suction inlet 13 s is formed in the peripheral wall of the secondcylinder block 13. The suction inlet 13 s is connected to the externalrefrigerant circuit. Refrigerant gas is drawn into the crank chamber 24from the external refrigerant circuit via the suction inlet 13 s and isthen drawn into the suction chambers 14 a, 15 a via the suction passages12 c, 13 c. The suction chambers 14 a, 15 a and the crank chamber 24 aretherefore in a suction pressure zone. The pressure in the suctionchambers 14 a, 15 a and the pressure in the crank chamber 24 aresubstantially equal to each other.

The rotary shaft 21 has an annular flange portion 21 f, which extends inthe radial direction. The flange portion 21 f is arranged in the firstlarge diameter hole 12 b. With respect to the axial direction of therotary shaft 21, a first thrust bearing 27 a is arranged between theflange portion 21 f and the first cylinder block 12. A cylindricalsupporting member 39 is press fitted to a rear portion of the rotaryshaft 21. The supporting member 39 has an annular flange portion 39 f,which extends in the radial direction. The flange portion 39 f isarranged in the second large diameter hole 13 b. With respect to theaxial direction of the rotary shaft 21, a second thrust bearing 27 b isarranged between the flange portion 39 f and the second cylinder block13.

An annular fixed body 31 is fixed to the rotary shaft 21 to beintegrally rotational with the rotary shaft 21. The fixed body 31 islocated rearward of the flange portion 21 f and forward of the swashplate 23. A cylindrical movable body 32 having a closed end is locatedbetween the flange portion 21 f and the fixed body 31. The movable body32 is movable along the axis of the rotary shaft 21 with respect to thefixed body 31.

The movable body 32 is formed by an annular bottom portion 32 a and acylindrical portion 32 b. An insertion hole 32 e is formed in the bottomportion 32 a to receive the rotary shaft 21. The cylindrical portion 32b extends along the axis of the rotary shaft 21 from the peripheral edgeof the bottom portion 32 a. The inner circumferential surface of thecylindrical portion 32 b is slidable along the outer circumferentialsurface of the fixed body 31. This allows the movable body 32 to rotateintegrally with the rotary shaft 21 via the fixed body 31. The clearancebetween the inner circumferential surface of the cylindrical portion 32b and the outer circumferential surface of the fixed body 31 is sealedby a sealing member 33. The clearance between the insertion hole 32 eand the rotary shaft 21 is sealed by a sealing member 34. The fixed body31 and the movable body 32 define a control pressure chamber 35 inbetween.

A first in-shaft passage 21 a is formed in the rotary shaft 21. Thefirst in-shaft passage 21 a extends along the axis L of the rotary shaft21. The rear end of the first in-shaft passage 21 a is opened to theinterior of the pressure adjusting chamber 15 c. A second in-shaftpassage 21 b is formed in the rotary shaft 21. The second in-shaftpassage 21 b extends in the radial direction of the rotary shaft 21. Oneend of the second in-shaft passage 21 b communicates with the firstin-shaft passage 21 a. The other end of the second in-shaft passage 21 bis opened to the interior of the control pressure chamber 35.Accordingly, the control pressure chamber 35 and the pressure adjustingchamber 15 c are connected to each other by the first in-shaft passage21 a and the second in-shaft passage 21 b.

In the crank chamber 24, a lug arm 40 is provided between the swashplate 23 and the flange portion 39 f. The lug arm 40 substantially hasan L shape extending from a first end to a second end. The lug arm 40has a weight portion 40 a formed at one end. The weight portion 40 aextends to a position in front of the swash plate 23 through a groove 23b of the swash plate 23.

The first end of the lug arm 40 is coupled to the upper side (upper sideas viewed in FIG. 1) of the swash plate 23 by a first pin 41, whichextends across the groove 23 b. This structure allows the first end ofthe lug arm 40 to be supported by the swash plate 23 such that the firstend of the lug arm 40 can pivot about a first pivot axis M1, whichcoincides with the axis of the first pin 41. The second end of the lugarm 40 is coupled to the supporting member 39 by a second pin 42. Thisstructure allows the second end of the lug arm 40 to be supported by thesupporting member 39 such that the second end of the lug arm 40 canpivot about a second pivot axis M2, which coincides with the axis of thesecond pin 42.

A coupling portion 32 c is formed at the distal end of the cylindricalportion 32 b of the movable body 32. The coupling portion 32 c protrudestoward the swash plate 23. The coupling portion 32 c has a movable bodyinsertion hole 32 h for receiving a third pin 43. The swash plate 23 hasa swash plate insertion hole 23 h for receiving the third pin 43 on thelower side (lower side as viewed in FIG. 1). The third pin 43 couplesthe coupling portion 32 c to the lower part of the swash plate 23.

The second valve plate 17 has a restriction 36 a, which communicateswith the discharge chamber 15 b. The second cylinder block 13 has acommunication portion 36 b in an end face that faces the second valveplate 17. The communication portion 36 b connects the pressure adjustingchamber 15 c and the restriction 36 a to each other. The dischargechamber 15 b and the control pressure chamber 35 are connected to eachother via the restriction 36 a, the communication portion 36 b, thepressure adjusting chamber 15 c, the first in-shaft passage 21 a, andthe second in-shaft passage 21 b. Therefore, the restriction 36 a, thecommunication portion 36 b, the pressure adjusting chamber 15 c, thefirst in-shaft passage 21 a, and the second in-shaft passage 21 b form asupply passage extending from the discharge chamber 15 b to the controlpressure chamber 35. The restriction 36 a reduces the opening degree ofthe supply passage.

The pressure in the control pressure chamber 35 is regulated byintroducing refrigerant gas from the discharge chamber 15 b to thecontrol pressure chamber 35 and discharging refrigerant gas from thecontrol pressure chamber 35 to the suction chamber 15 a. Thus, therefrigerant gas introduced into the control pressure chamber 35 servesas control gas for regulating the pressure in the control pressurechamber 35. The pressure difference between the control pressure chamber35 and the crank chamber 24 causes the movable body 32 to move along theaxis of the rotary shaft 21 with respect to the fixed body 31. Anelectromagnetic displacement control valve 50 for controlling thepressure in the control pressure chamber 35 is installed in the rearhousing member 15. The displacement control valve 50 is electricallyconnected to a control computer 50 c. Signaling connection is providedbetween the control computer 50 c and an air conditioner switch 50 s.

As shown in FIG. 2, a valve housing 50 h of the displacement controlvalve 50 includes a cylindrical first housing member 51, whichaccommodates an electromagnetic solenoid 53, a cylindrical secondhousing member 52, which has a closed end and attached to the firsthousing member 51, and a lid member 52 f, which closes an opening of thesecond housing member 52 that is located on the opposite side to thefirst housing member 51. The lid member 52 f is press fitted in theopening of the second housing member 52.

The electromagnetic solenoid 53 has a fixed iron core 54 and a movableiron core 55, which is attracted to the fixed iron core 54 based onexcitation by current supplied to a coil 53 c. The fixed iron core 54 isarranged to be closer to the second housing member 52 than the movableiron core 55 is to the second housing member 52. The electromagneticforce of the electromagnetic solenoid 53 attracts the movable iron core55 toward the fixed iron core 54. The electromagnetic solenoid 53 issubjected to current control (duty cycle control) performed by thecontrol computer 50 c. A spring 56 is located between the fixed ironcore 54 and the movable iron core 55. The spring 56 urges the movableiron core 55 away from the fixed iron core 54.

A pillar-like drive force transmitting member 57 is attached to themovable iron core 55. The drive force transmitting member 57 is allowedto move integrally with the movable iron core 55. A back pressurechamber 58 is defined between a bottom wall 52 e of the second housingmember 52 and the fixed iron core 54. The drive force transmittingmember 57 extends through the fixed iron core 54 and projects into theback pressure chamber 58. The fixed iron core 54 has a recess 54 e,which is formed in an end face of the fixed iron core 54 that is closeto the bottom wall 52 e of the second housing member 52 and surroundsthe drive force transmitting member 57. The recess 54 e and the bottomwall 52 e define the back pressure chamber 58.

An accommodating chamber 59 is formed in the second housing member 52.The accommodating chamber 59 accommodates a pressure sensing mechanism60. The pressure sensing mechanism 60 is formed by a support 61, abellows 62, a pressure receiving body 63, and a spring 64. The support61 is capable of contacting and separating from an end face of the lidmember 52 f that faces the accommodating chamber 59. The bellows 62 canextend and contract and has an end coupled to the support 61. Thepressure receiving body 63 is coupled to the other end of the bellows62. The spring 64 is arranged in the bellows 62 to urges the support 61and the pressure receiving body 63 away from each other.

The bellows 62 accommodates a stopper 61 a, which is integrally formedwith the support 61. The pressure receiving body 63 has a stopper 63 a,which protrudes toward the stopper 61 a of the support 61. The stopper61 a of the support 61 and the stopper 63 a of the pressure receivingbody 63 define the smallest length of the bellows 62.

A recess 52 a, which is continuous with the accommodating chamber 59, isformed in the bottom wall 52 e of the second housing member 52. Further,an annular valve seat member 65, which has a valve hole 65 h, isarranged in the accommodating chamber 59 at a position close to thebottom wall 52 e. The valve seat member 65 is formed separately from thesecond housing member 52. The end face of the valve seat member 65 thatfaces the recess 52 a is flat and contacts a step 52 b formed betweenthe accommodating chamber 59 and the recess 52 a with each other. Thevalve seat member 65 has an annular projection 65 a formed on the innerend face, which faces the pressure sensing mechanism 60. The projection65 a projects toward the pressure sensing mechanism 60.

The accommodating chamber 59 accommodates an urging spring 66. Theurging spring 66 is located between the valve seat member 65 and the lidmember 52 f. The end of the urging spring 66 that faces the lid member52 f is coupled to the lid member 52 f, and the end of the urging spring66 that faces the valve seat member 65 is coupled to a part of the valveseat member 65 that is outside the projection 65 a. Since the projection65 a is located in the urging spring 66, the urging spring 66 isprevented from moving toward the projection 65 a by the projection 65 a.The valve seat member 65 is pressed against the step 52 b by the urgingspring 66 so that the position of the valve seat member 65 isdetermined.

A valve chamber 67 is defined between the valve seat member 65 and therecess 52 a in the second housing member 52. The second housing member52 accommodates a valve member 68, which extends through the bottom wall52 e of the second housing member 52. The valve member 68 also extendsthrough the valve chamber 67 and the valve hole 65 h from the backpressure chamber 58 to the accommodating chamber 59. The valve member 68has a first valve body 68 v, which is accommodated in the valve chamber67. The valve member 68 has a pillar-like projection 68 a on an end facethat is located in the accommodating chamber 59. The projection 68 a iscoupled to the pressure receiving body 63. That is, the valve member 68is integrated with the pressure sensing mechanism 60.

On the end face of the valve seat member 65 that faces the recess 52 a,a valve seat 65 e, on which the first valve body 68 v is seated, isformed about the valve hole 65 h. Therefore, the valve seat member 65has the valve seat 65 e, on which the first valve body 68 v is seated.The first valve body 68 v is capable of opening and closing the valvehole 65 h by separating from and contacting the valve seat 65 e. Acylindrical guide wall 69 is formed in the bottom wall 52 e of thesecond housing member 52. The guide wall 69 guides the valve member 68in the moving direction of the drive force transmitting member 57. Theback pressure chamber 58 is located between the electromagnetic solenoid53 and the valve chamber 67. The valve chamber 67 and the back pressurechamber 58 are connected to each other via a clearance 69 s between theguide wall 69 and the valve member 68. A communication passage 75, whichconnects the valve chamber 67 and the back pressure chamber 58 to eachother, is formed in the bottom wall 52 e of the second housing member52. The back pressure chamber 58 is connected to an accommodatingchamber 55 a, which accommodates the movable iron core 55, via aclearance between the drive force transmitting member 57 and the fixediron core 54.

The accommodating chamber 59 communicates with the pressure adjustingchamber 15 c through a passage 71. The valve chamber 67 communicateswith the suction chamber 15 a through a passage 72. Accordingly, thesecond in-shaft passage 21 b, the first in-shaft passage 21 a, thepressure adjusting chamber 15 c, the passage 71, the accommodatingchamber 59, the valve hole 65 h, the valve chamber 67, and the passage72 form a discharge passage extending from the control pressure chamber35 to the suction chamber 15 a.

The cross-sectional area of the valve hole 65 h, which is selectivelyopened and closed by the first valve body 68 v, is equal to theeffective pressure receiving area of the bellows 62. Therefore, when thefirst valve body 68 v is closed, the pressure sensing mechanism 60 isnot influenced by the pressure in the accommodating chamber 59. Thebellows 62 senses the pressure that is applied to the valve member 68 inthe back pressure chamber 58, thereby either extending or contracting inthe moving direction of the drive force transmitting member 57.Extension and contraction of the bellows 62 is used to position thefirst valve body 68 v and contributes to the adjustment of the valveopening degree of the first valve body 68 v. The opening degree of thefirst valve body 68 v is determined by the balance of theelectromagnetic force produced by the electromagnetic solenoid 53, theforce of the spring 56, and the urging force of the pressure sensingmechanism 60.

The first valve body 68 v adjusts the opening degree (passagecross-sectional area) of the discharge passage. When the first valvebody 68 v is seated on the valve seat 65 e, the discharge passage isclosed. In contrast, when the first valve body 68 v separates from thevalve seat 65 e, the discharge passage is open.

A communicating chamber 73 is formed inside the lid member 52 f. Thecommunicating chamber 73 is located on the opposite side of the pressuresensing mechanism 60 to the valve chamber 67. The communicating chamber73 is open on the side opposite to the accommodating chamber 59 and isconnected to the suction chamber 15 a via a passage 73 a. Thecommunicating chamber 73 accommodates a valve opening spring 73 f, whichurges the pressure sensing mechanism 60 and the valve member 68 towardthe electromagnetic solenoid 53. The urging force of the valve openingspring 73 f, which urges the pressure sensing mechanism 60 and the valvemember 68 toward the electromagnetic solenoid 53, is set to be smallerthan the urging force of the spring 64, which urges the support 61 andthe pressure receiving body 63 away from each other.

When the pressure in the communicating chamber 73 exceeds apredetermined pressure (for example, 0.35 MPag), the pressure sensingmechanism 60 senses the pressure and contracts in the moving directionof the drive force transmitting member 57. Accordingly, the support 61separates from the end face of the lid member 52 f that faces theaccommodating chamber 59, so that the support 61 opens the communicatingchamber 73. When the support 61 contacts the end face of the lid member52 f that faces the accommodating chamber 59, the support 61 closes thecommunicating chamber 73. Therefore, the support 61 functions as asecond valve body, which is located in the pressure sensing mechanism 60and opens and closes the communicating chamber 73. The cross-sectionalarea of the communicating chamber 73, which selectively is opened andclosed by the support 61, is equal to the effective pressure receivingarea of the support 61. Therefore, when the first support 61 is closed,the pressure sensing mechanism 60 is not influenced by the pressure inthe accommodating chamber 59.

A contraction allowance S1 of the pressure sensing mechanism 60 in themoving direction of the drive force transmitting member 57 (the distancebetween the stopper 61 a of the support 61 and the stopper 63 a of thepressure receiving body 63 when the valve opening degree of the firstvalve body 68 v is maximized) is set to be smaller than a movable rangeR1 of the drive force transmitting member 57.

Operation of the present embodiment will now be described.

When the air conditioner switch 50 s is turned on, current is suppliedto the electromagnetic solenoid 53 of the variable displacement swashplate type compressor 10, which has the above described configuration.At this time, the electromagnetic force of the electromagnetic solenoid53 attracts the movable iron core 55 toward the fixed iron core 54against the force of the spring 56 as shown in FIG. 3. Then, the driveforce transmitting member 57 pushes the valve member 68. Accordingly,the valve opening degree of the first valve body 68 v is reduced. Thisreduces the flow rate of refrigerant gas that is discharged from thecontrol pressure chamber 35 to the suction chamber 15 a via the secondin-shaft passage 21 b, the first in-shaft passage 21 a, the pressureadjusting chamber 15 c, the passage 71, the accommodating chamber 59,the valve hole 65 h, the valve chamber 67, and the passage 72. Sincerefrigerant gas is introduced into the control pressure chamber 35 fromthe discharge chamber 15 b via the restriction 36 a, the communicationportion 36 b, the pressure adjusting chamber 15 c, the first in-shaftpassage 21 a, and the second in-shaft passage 21 b, the pressure in thecontrol pressure chamber 35 approaches the pressure in the dischargechamber 15 b.

When the pressure difference between the control pressure chamber 35 andthe crank chamber 24 is increased, the movable body 32 is moved suchthat the bottom portion 32 a of the movable body 32 is separated awayfrom the fixed body 31 as shown in FIG. 4. This causes the swash plate23 to pivot about the first pivot axis M1. As the swash plate 23 pivotsabout the first pivot axis M1, the ends of the lug arm 40 pivot aboutthe first pivot axis M1 and the second pivot axis M2, respectively, sothat the lug arm 40 is separated away from the flange portion 39 f ofthe supporting member 39. This increases the inclination angle of theswash plate 23 and thus increases the stroke of the double-headedpistons 25. Accordingly, the displacement is increased. The movable body32 is configured to contact the flange portion 21 f when the swash plate23 reaches the maximum inclination angle. The contact between themovable body 32 and the flange portion 21 f maintains the maximuminclination angle of the swash plate 23.

An increase in the valve opening degree of the first valve body 68 v asshown in FIG. 2 increases the flow rate of refrigerant gas that isdischarged from the control pressure chamber 35 to the suction chamber15 a via the second in-shaft passage 21 b, the first in-shaft passage 21a, the pressure adjusting chamber 15 c, the passage 71, theaccommodating chamber 59, the valve hole 65 h, the valve chamber 67, andthe passage 72, so that the pressure in the control pressure chamber 35approaches the pressure in the suction chamber 15 a.

When the pressure difference between the control pressure chamber 35 andthe crank chamber 24 is decreased, the movable body 32 is moved suchthat the bottom portion 32 a of the movable body 32 approaches the fixedbody 31 as shown in FIG. 1. This causes the swash plate 23 to pivotabout the first pivot axis M1 in a direction opposite to the pivotingdirection for increasing the inclination angle of the swash plate 23. Asthe swash plate 23 pivots about the first pivot axis M1 in a directionopposite to the inclination angle increasing direction, the ends of thelug arm 40 pivot about the first pivot axis M1 and the second pivot axisM2, respectively, in a direction opposite to the pivoting direction forincreasing the inclination angle of the swash plate 23, so that the lugarm 40 approaches the flange portion 39 f of the supporting member 39.This reduces the inclination angle of the swash plate 23 and thusreduces the stroke of the double-headed pistons 25. Accordingly, thedisplacement is decreased. The lug arm 40 is configured to contact theflange portion 39 f of the supporting member 39 when the swash plate 23reaches the minimum inclination angle. The contact between the lug arm40 and the flange portion 39 f maintains the minimum inclination angleof the swash plate 23.

When the air conditioner switch 50 s is turned off, the current supplyto the electromagnetic solenoid 53 is stopped. At this time, if thepressure in the suction chamber 15 a is higher than a predeterminedpressure, the pressure in the back pressure chamber 58, which is asuction pressure zone, is raised. Therefore, the pressure in the backpressure chamber 58 acts to move the first valve body 68 v in adirection closing the discharge passage.

When the pressure in the suction chamber 15 a is higher than thepredetermined pressure, the pressure sensing mechanism 60 senses thatthe pressure in the communicating chamber 73 is higher than thepredetermined pressure and contracts in the moving direction of thedrive force transmitting member 57 as shown in FIG. 5. Accordingly, thesupport 61 separates from the end face of the lid member 52 f that facesthe accommodating chamber 59, so that the communicating chamber 73 isopened. Further, the valve opening spring 73 f urges the pressuresensing mechanism 60 and the valve member 68 toward the electromagneticsolenoid 53. Accordingly, the support 61 is maintained separated from anend face of the lid member 52 f that corresponds to the accommodatingchamber 59. As a result, refrigerant gas from the control pressurechamber 35 is delivered to the suction chamber 15 a via the secondin-shaft passage 21 b, the first in-shaft passage 21 a, the pressureadjusting chamber 15 c, the passage 71, the accommodating chamber 59,the communicating chamber 73, and the passage 73 a. This allows thepressure in the control pressure chamber 35 to be substantially equal tothe pressure in the suction chamber 15 a. Therefore, when no current issupplied to the electromagnetic solenoid 53, the swash plate 23 is movedto and maintained at the minimum inclination angle.

Further, since the valve opening spring 73 f urges the pressure sensingmechanism 60 and the valve member 68 toward the electromagnetic solenoid53, the first valve body 68 v is maintained separated from the valveseat 65 e. Accordingly, the refrigerant gas is discharged from thecontrol pressure chamber 35 to the suction chamber 15 a via the secondin-shaft passage 21 b, the first in-shaft passage 21 a, the pressureadjusting chamber 15 c, the passage 71, the accommodating chamber 59,the valve hole 65 h, the valve chamber 67, and the passage 72. That is,the discharge of refrigerant gas from the control pressure chamber 35 tothe suction chamber 15 a via the discharge passage and the discharge ofrefrigerant gas from the control pressure chamber 35 to the suctionchamber 15 a via the accommodating chamber 59 and the communicatingchamber 73 are performed simultaneously. Therefore, compared to a casein which discharge of refrigerant gas from the control pressure chamber35 to the suction chamber 15 a is performed only via the accommodatingchamber 59 and the communicating chamber 73, the flow rate ofrefrigerant gas that is discharged from the control pressure chamber 35to the suction chamber 15 a is increased, so that the inclination angleof the swash plate 23 is smoothly minimized.

Thereafter, when the air conditioner switch 50 s is turned on andcurrent supply to the electromagnetic solenoid 53 is resumed, thevariable displacement swash plate type compressor 10 is operated at theminimum displacement. Thus, the load on the variable displacement swashplate type compressor 10 is prevented from being increased due to anabrupt increase in the displacement.

FIG. 6 illustrates a state in which the pressure sensing mechanism 60senses that the pressure in the communicating chamber 73 exceeds thepredetermined pressure, and the stopper 61 a of the support 61 and thestopper 63 a of the pressure receiving body 63 contact each other, sothat the bellows 62 is contracted to the smallest length. Suppose that,in this state, the air conditioner switch 50 s is turned on to supplycurrent to the electromagnetic solenoid 53. In this case, the movableiron core 55 is attracted toward the fixed iron core 54 and the driveforce transmitting member 57 pushes the valve member 68. This causes thefirst valve body 68 v to be seated on the valve seat 65 e to close thedischarge passage.

At this time, since the pressure sensing mechanism 60 is contracted inthe moving direction of the drive force transmitting member 57, aclearance H1 is formed between the support 61 and the end face of thelid member 52 f that faces the accommodating chamber 59. Further, thecontraction allowance S1 of the pressure sensing mechanism 60 in themoving direction of the drive force transmitting member 57 is set to besmaller than the movable range R1 of the drive force transmitting member57. Therefore, between the movable iron core 55 and the fixed iron core54, a clearance H2 remains that is greater than the clearance H1 betweenthe support 61 and the end face of the lid member 52 f that faces theaccommodating chamber 59.

In a state in which the first valve body 68 v is seated on the valveseat 65 e as shown in FIG. 7, if the movable iron core 55 is furtherattracted to the fixed iron core 54, the drive force transmitting member57 is actuated to push the pressure sensing mechanism 60 and the valvemember 68 toward the communicating chamber 73. At this time, since thevalve seat member 65 is formed separately from the valve housing 50 h,the valve seat member 65 is moved toward the communicating chamber 73with respect to the valve housing 50 h. Accordingly, even if the bellows62 is in the most contracted state with the stopper 61 a of the support61 and the stopper 63 a of the pressure receiving body 63 contactingeach other, the support 61 will be returned to a position where thesupport 61 contacts the end face of the lid member 52 f that faces theaccommodating chamber 59 and closes the communicating chamber 73.

Thus, the first valve body 68 v and the support 61 close to stopdischarge of refrigerant gas from the control pressure chamber 35 to thesuction chamber 15 a via the discharge passage and discharge ofrefrigerant gas from the control pressure chamber 35 to the suctionchamber 15 a via the accommodating chamber 59 and the communicatingchamber 73.

Since refrigerant gas is introduced into the control pressure chamber 35from the discharge chamber 15 b via the restriction 36 a, thecommunication portion 36 b, the pressure adjusting chamber 15 c, thefirst in-shaft passage 21 a, and the second in-shaft passage 21 b, thepressure in the control pressure chamber 35 approaches the pressure inthe discharge chamber 15 b. Accordingly, the inclination angle of theswash plate 23 is increased.

When the pressure in the suction chamber 15 a drops from thepredetermined pressure, and the pressure sensing mechanism 60 isgradually extended from the contracted state in the moving direction ofthe drive force transmitting member 57, the first valve body 68 v ismoved toward the electromagnetic solenoid 53. At this time, since thevalve seat member 65 is urged toward the first valve body 68 v by theurging spring 66, the valve seat member 65 is moved toward theelectromagnetic solenoid 53 while following the movement of the firstvalve body 68 v toward the electromagnetic solenoid 53. Thus, the firstvalve body 68 v is maintained seated on the valve seat 65 e.

In a case in which the rotary shaft 21 receives rotational drive forcefrom the engine E via the power transmission mechanism PT, which is aclutchless mechanism, the rotational drive force is constantlytransmitted to the rotary shaft 21 from the engine E via the powertransmission mechanism PT even if no current is supplied to theelectromagnetic solenoid 53. Therefore, the power of the engine E isconsumed slightly. Therefore, to minimize consumption of the power ofthe engine E, minimum displacement operation, in which the swash plate23 is maintained at the minimum inclination angle, is preferable in astate in which no current is supplied to the electromagnetic solenoid53.

Therefore, when no current is supplied to the electromagnetic solenoid53, the opening degree of the first valve body 68 v is maximized so thatrefrigerant gas is discharged from the control pressure chamber 35 tothe suction chamber 15 a via the discharge passage. Accordingly, thedisplacement control valve 50 substantially equalizes the pressure inthe control pressure chamber 35 with the pressure in the suction chamber15 a and minimizes the inclination angle of the swash plate 23. However,if the pressure in the suction chamber 15 a exceeds the predeterminedpressure when no current is supplied to the electromagnetic solenoid 53,the pressure in the back pressure chamber 58 is increased. In this case,the pressure in the back pressure chamber 58 causes the first value body68 v to close the discharge passage, which is undesirable.

In this respect, according to the present embodiment, the pressuresensing mechanism 60 is contracted in the moving direction of the driveforce transmitting member 57 when the pressure in the communicatingchamber 73 is higher than the predetermined pressure. Accordingly, thesupport 61 separates from the end face of the lid member 52 f that facesthe accommodating chamber 59, so that the support 61 opens thecommunicating chamber 73. As a result, refrigerant gas from the controlpressure chamber 35 is delivered to the suction chamber 15 a via thesecond in-shaft passage 21 b, the first in-shaft passage 21 a, thepressure adjusting chamber 15 c, the passage 71, the accommodatingchamber 59, the communicating chamber 73, and the passage 73 a.

This allows the pressure in the control pressure chamber 35 to besubstantially equal to the pressure in the suction chamber 15 a when thecurrent supply to the electromagnetic solenoid 53 is stopped. Therefore,the inclination angle of the swash plate 23 is minimized. Thus, in astate in which no current is supplied to the electromagnetic solenoid 53in a configuration in which the rotary shaft 21 receives rotationaldrive force from the engine E via the power transmission mechanism PT,which is a clutchless mechanism, the inclination angle of the swashplate 23 is changed to and maintained at the minimum inclination even ifthe pressure in the suction chamber 15 a changes. This ensures theminimum displacement operation. As a result, the power consumption ofthe engine E is minimized.

The above described embodiment provides the following advantages.

(1) The displacement control valve 50 has the communicating chamber 73,which is located on the opposite side of the pressure sensing mechanism60 to the valve chamber 67 and communicates with the suction chamber 15a, and the support 61, which is located in the pressure sensingmechanism 60 and opens and closes the communicating chamber 73. When thecurrent supply to the electromagnetic solenoid 53 is stopped and thepressure in the communicating chamber 73 is higher than thepredetermined pressure, the pressure sensing mechanism 60 is contractedin the moving direction of the drive force transmitting member 57, sothat the support 61 opens. If the pressure in the suction chamber 15 aexceeds the predetermined pressure when no current is supplied to theelectromagnetic solenoid 53, the pressure in the suction chamber 15 aacts to move the first valve body 68 v in a direction closing thedischarge passage.

With this being the situation, the pressure sensing mechanism 60 iscontracted in the moving direction of the drive force transmittingmember 57 when the pressure in the communicating chamber 73 is higherthan the predetermined pressure so that the support 61 opens. Thisallows the refrigerant gas in the control pressure chamber 35 to bedischarged to the suction chamber 15 a via the accommodating chamber 59and the communicating chamber 73. As a result, the pressure in thecontrol pressure chamber 35 is substantially equalized with the pressurein the suction chamber 15 a. Therefore, even if the pressure in thesuction chamber 15 a changes when no current is supplied to theelectromagnetic solenoid 53, the inclination angle of the swash plate 23is changed to and maintained at the minimum inclination angle.

(2) The communicating chamber 73 accommodates a valve opening spring 73f, which urges the pressure sensing mechanism 60 and the valve member 68toward the electromagnetic solenoid 53. Therefore, even if the pressurein the suction chamber 15 a is increased when no current is supplied tothe electromagnetic solenoid 53, and the pressure in the suction chamber15 a acts to move the first valve body 68 v in the direction closing thedischarge passage, the valve opening spring 73 f urges the pressuresensing mechanism 60 and the valve member 68 toward the electromagneticsolenoid 53.

The discharge passage is thus prevented from being closed by the firstvalve body 68 v. Thus, the discharge of refrigerant gas from the controlpressure chamber 35 to the suction chamber 15 a via the dischargepassage and the discharge of refrigerant gas from the control pressurechamber 35 to the suction chamber 15 a via the accommodating chamber 59and the communicating chamber 73 can be performed simultaneously.Therefore, compared to a case in which discharge of refrigerant gas fromthe control pressure chamber 35 to the suction chamber 15 a is performedonly via the accommodating chamber 59 and the communicating chamber 73,the flow rate of refrigerant gas that is discharged from the controlpressure chamber 35 to the suction chamber 15 a can be increased, sothat the inclination angle of the swash plate 23 can be smoothlyminimized.

(3) The valve seat 65 e, on which the first valve body 68 v is seated,is formed on the valve seat member 65, and the valve seat member 65 isformed separately from the valve housing 50 h. In this configuration,when the first valve body 68 v is seated on the valve seat 65 e, thedrive force transmitting member 57 is actuated to move the pressuresensing mechanism 60 and the valve member 68 toward the communicatingchamber 73. Therefore, even if the pressure sensing mechanism 60 is in acontracted state in the moving direction of the drive force transmittingmember 57, the support 61 is returned to the position to close thecommunicating chamber 73.

(4) The accommodating chamber 59 accommodates the urging spring 66,which urges the valve seat member 65 toward the first valve body 68 v.When the pressure in the suction chamber 15 a drops from thepredetermined pressure, and the pressure sensing mechanism 60 isgradually extended from the contracted state in the moving direction ofthe drive force transmitting member 57, the first valve body 68 v ismoved toward the electromagnetic solenoid 53. At this time, since thevalve seat member 65 is urged toward the first valve body 68 v by theurging spring 66, the valve seat member 65 can be moved toward theelectromagnetic solenoid 53 while following the movement of the firstvalve body 68 v toward the electromagnetic solenoid 53. Thus, the firstvalve body 68 v can be maintained seated on the valve seat 65 e.

(5) The communicating chamber 73 is open on the side opposite to theaccommodating chamber 59 and communicates with the suction chamber 15 a.This simplifies the structure of the displacement control valve 50compared to a case in which, for example, the communicating chamber 73and the back pressure chamber 58 are connected by a communicationpassage so that communicating chamber 73 and the back pressure chamber58 are connected to each other.

(6) The contraction allowance S1 of the pressure sensing mechanism 60 inthe moving direction of the drive force transmitting member 57 is set tobe smaller than the movable range R1 of the drive force transmittingmember 57. In this configuration, when the current supply to theelectromagnetic solenoid 53 is performed, the first valve body 68 v andthe support 61 are reliably closed.

(7) According to the present embodiment, the inclination angle of theswash plate 23 can be minimized when the current supply to theelectromagnetic solenoid 53 is stopped. Therefore, when the currentsupply to the electromagnetic solenoid 53 is resumed, the variabledisplacement swash plate type compressor 10 is operated at the minimumdisplacement. Thus, the load on the variable displacement swash platetype compressor 10 is prevented from being increased due to an abruptincrease in the displacement.

(8) The variable displacement swash plate type compressor 10 of thepresent embodiment receives rotational drive force from the engine E viathe power transmission mechanism PT, which is a clutchless mechanism.This configuration reduces the weight of the entire variabledisplacement swash plate type compressor 10 and the electricityconsumption for driving the power transmission mechanism, which is anelectromagnetic clutch mechanism, compared to a case in which the rotaryshaft 21 receives rotational drive force from the engine E via a powertransmission mechanism that is an electromagnetic clutch mechanism onlywhen current is supplied to the electromagnetic solenoid 53.

(9) According to the present embodiment, in a state in which no currentis supplied to the electromagnetic solenoid 53 in a configuration inwhich the rotary shaft 21 receives rotational drive force from theengine E via the power transmission mechanism PT, which is a clutchlessmechanism, the inclination angle of the swash plate 23 is changed to andmaintained at the minimum inclination even if the pressure in thesuction chamber 15 a is higher than the predetermined pressure. Thisreliably allows the operation at the minimum displacement. As a result,the power consumption of the engine E is minimized.

(10) The displacement control valve 50 has the guide wall 69, whichguides the valve member 68 in the moving direction of the drive forcetransmitting member 57. The valve chamber 67 and the back pressurechamber 58 are connected to each other via the clearance 69 s betweenthe guide wall 69 and the valve member 68. Since the valve member 68 isguided by the guide wall 69, the valve member 68 is prevented from beingtilted with respect to the moving direction, so that the first valvebody 68 v is guided to a reliable closed state. Since the clearance 69 sis formed between the guide wall 69 and the valve member 68, the valvemember 68 moves smoothly. This allows the first valve body 68 v to movesmoothly. The responsiveness of the displacement control valve 50 isimproved accordingly.

(11) The valve chamber 67 and the back pressure chamber 58 are connectedto each other by the communication passage 75. This configurationshortens the time for the pressure in the back pressure chamber 58 to beequalized with the pressure in the suction chamber 15 a, which is equalto the valve chamber 67, compared to a case in which, for example, thevalve chamber 67 and the back pressure chamber 58 are connected to eachother only by the clearance 69 s between the guide wall 69 and the valvemember 68 without providing the communication passage 75.

(12) The urging spring 66 for urging the valve seat member 65 toward thefirst valve body 68 v is located between the valve seat member 65 andthe lid member 52 f. In this configuration, before the lid member 52 f,the pressure sensing mechanism 60, the valve seat member 65, and thevalve member 68 are installed in the valve housing 50 h, the urgingspring 66 urges the valve seat member 65 toward the first valve body 68v. Therefore, the lid member 52 f, the pressure sensing mechanism 60,the valve seat member 65, and the valve member 68 are assembled as aunit via the urging spring 66. Compared to a case in which the lidmember 52 f, the pressure sensing mechanism 60, the valve seat member65, and the valve member 68 are independent, the unit can be easilyinstalled in the valve housing 50 h.

Since the urging spring 66 is located between the valve seat member 65and the lid member 52 f, the positions of the valve seat member 65 andthe pressure sensing mechanism 60 can be adjusted by using the urgingspring 66 during assembly. This allows the positions of the valve seatmember 65 and the pressure sensing mechanism 60 to be easily determined.

The above described embodiment may be modified as follows.

As shown in FIG. 8, the displacement control valve 50 may have acommunication passage 77, which connects the communicating chamber 73and the back pressure chamber 58 to each other. Further, thecommunicating chamber 73 may be connected to the suction chamber 15 a byconnecting the communicating chamber 73 and the back pressure chamber 58to each other by the communication passage 77. The communication passage77 is formed by an annular groove 77 a, which is formed on the outersurface of the lid member 52 f, a through hole 77 b, which is formed inthe lid member 52 f to connect the annular groove 77 a with thecommunicating chamber 73, and a communication passage 77 c, which isformed in the second housing member 52 to connect the annular groove 77a with the back pressure chamber 58.

As shown in FIG. 9, the back pressure chamber 58 may be omitted, and thedrive force transmitting member 57 may be integrated with the valvemember 68.

In the illustrated embodiment, the urging spring 66 may be omitted. Inthis case, at the assembly of the valve housing 50 h, refrigerant gas isintroduced from the control pressure chamber 35 to the accommodatingchamber 59 with the pressure sensing mechanism 60, the valve seat member65, and the valve member 68 arranged in the valve housing 50 h, so thatthe valve seat member 65 is pressed against the step 52 b by thepressure of the refrigerant gas introduced into the accommodatingchamber 59. The valve seat member 65 is positioned by pressing the valveseat member 65 against the step 52 b by the pressure of the refrigerantgas.

In the illustrated embodiment, a valve seat on which the first valvebody 68 v is seated may be formed integrally with the valve housing 50h.

In the illustrated embodiment, the valve opening spring 73 f may beomitted.

In the illustrated embodiment, for example, the back pressure chamber 58may be defined by the fixed iron core 54 and a recess that is formed inthe bottom wall 52 e of the second housing member 52 that faces thefixed iron core 54 and surrounds the drive force transmitting member 57.

In the illustrated embodiment, the valve chamber 67 may be connected tothe suction chamber 14 a via the passage 72 as long as a dischargepassage is formed from the control pressure chamber 35 to the suctionpressure zone.

In the illustrated embodiment, the discharge chamber 14 b and thecontrol pressure chamber 35 may be connected to each other via therestriction 36 a, the communication portion 36 b, the pressure adjustingchamber 15 c, the first in-shaft passage 21 a, and the second in-shaftpassage 21 b.

In the illustrated embodiment, the cross-sectional area of the valvehole 65 h and the effective pressure receiving area of the bellows 62 donot necessarily need to be exactly the same as long as these areas aresubstantially equal to each other.

In the illustrated embodiment, the cross-sectional area of thecommunicating chamber 73 and the effective pressure receiving area ofthe support 61 do not necessarily need to be exactly the same as long asthese areas are substantially equal to each other.

In the illustrated embodiment, drive power may be obtained from anexternal drive source via a clutch.

In the illustrated embodiment, the variable displacement swash platetype compressor 10 is a double-headed piston swash plate type compressorhaving the double-headed pistons 25, but may be a single-headed pistonswash plate type compressor having single-headed pistons.

Therefore, the present examples and embodiments are to be considered asillustrative and not restrictive and the invention is not to be limitedto the details given herein, but may be modified within the scope andequivalence of the appended claims.

1. A variable displacement swash plate type compressor comprising: ahousing having a crank chamber; a swash plate accommodated in the crankchamber, wherein the swash plate receives a drive force from a rotaryshaft to rotate and is capable of changing its inclination anglerelative to the rotary shaft; a piston engaged with the swash plate; amovable body, which is coupled to the swash plate and changes theinclination angle of the swash plate; a control pressure chamber definedin the housing by the movable body, wherein pressure in the controlpressure chamber is changed by introducing control gas therein so thatthe movable body is moved in the axial direction of the rotary shaft;and a displacement control valve that controls the pressure in thecontrol pressure chamber, wherein the piston is reciprocated by a strokethat corresponds to the inclination angle of the swash plate, thedisplacement control valve includes: a drive force transmitting member,which is driven by an electromagnetic solenoid; a valve member having afirst valve body, wherein the first valve body adjusts an opening degreeof discharge passage that extends from the control pressure chamber to asuction pressure zone; a valve chamber, which accommodates the firstvalve body and communicates with the suction pressure zone; anaccommodating chamber, which communicates with the control pressurechamber; a pressure sensing mechanism, which is accommodated in theaccommodating chamber and integrated with the valve member, wherein, bysensing a pressure in the suction pressure zone that acts on the valvemember, the pressure sensing mechanism extends or contracts in themoving direction of the drive force transmitting member, therebyadjusting the valve opening degree of the first valve body; acommunicating chamber, which is located on the opposite side of thepressure sensing mechanism from the valve chamber and communicates withthe suction pressure zone; and a second valve body, which is located inthe pressure sensing mechanism and selectively opens and closes thecommunicating chamber, and when a current supply to the electromagneticsolenoid is stopped and the pressure in the suction pressure zone in thecommunicating chamber is higher than a predetermined pressure, thepressure sensing mechanism contracts in the moving direction of thedrive force transmitting member, thereby opening the second valve body.2. The variable displacement swash plate type compressor according toclaim 1, further comprising a valve opening spring, which is provided inthe communicating chamber and urges the pressure sensing mechanism andthe valve member toward the electromagnetic solenoid.
 3. The variabledisplacement swash plate type compressor according to claim 1, whereinthe displacement control valve further includes: a valve housing; and avalve seat member, which is formed separately from the valve housing,wherein the valve seat member has a valve seat, on which the first valvebody is seated.
 4. The variable displacement swash plate type compressoraccording to claim 3, further comprising an urging spring, which isprovided in the accommodating chamber and urges the valve seat membertoward the first valve body.
 5. The variable displacement swash platetype compressor according to claim 1, wherein the communicating chamberis open on the side opposite to the accommodating chamber andcommunicates with the suction pressure zone.
 6. The variabledisplacement swash plate type compressor according to claim 1, wherein acontraction allowance of the pressure sensing mechanism in the movingdirection of the drive force transmitting member is set to be smallerthan a movable range of the drive force transmitting member.
 7. Thevariable displacement swash plate type compressor according to claim 1,wherein the piston is a double-headed piston.
 8. The variabledisplacement swash plate type compressor according to claim 1, whereinthe rotary shaft receives drive force from an external drive source viathe power transmission mechanism, which is a clutchless mechanism.